Michelle Williams dove into her role as Marilyn Monroe. The Weinstein Company

A lot of actors will go to extremes for their movie roles, especially if there's a chance it can land them an Oscar nod.

Anne Hathaway was willing to do anything to understand the misery of her tuberculosis-ridden prostitute in "Les Misérables," while Rooney Mara and Kate Winslet found themselves taking their characters off set.

From dropping acid to strapping their knees with belts, these actors prove they're willing do anything to play the part.

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Jared Leto couldn't see anyone while filming "Blade Runner: 2049."

For his latest role in the "Blade Runner" sequel, Leto wore custom contact lenses which made his eyes opaque the entire time he was on set and blocked his sight. While Leto didn't feel the transformation was all that extreme, director Denis Villeneuve was taken with the actor's commitment.

"He entered the room, and he could not see at all," Villeneuve told the Wall Street Journal. "He was walking with an assistant, very slowly. It was like seeing Jesus walking into a temple. Everybody became super silent, and there was a kind of sacred moment. Everyone was in awe."

"I did a lot of things to create a dynamic, to create an element of surprise, of spontaneity, and to really break down any kind of walls that may be there," Leto told E!. "The Joker is somebody who doesn't really respect things like personal space or boundaries."

Anne Hathaway lost 25 pounds for her role in "Les Mis."

"I had to be obsessive about it — the idea was to look near death," said Hathaway. "Looking back on the whole experience — and I don't judge it in any way — it was definitely a little nuts. It was definitely a break with reality, but I think that's who [my character] Fantine is anyway."

Heath Ledger locked himself in his apartment for a month.

Heath Ledger's performance as the Joker was Oscar-worthy.
Warner Bros.

Ledger nearly descended into madness for his Oscar-winning role as The Joker in "The Dark Knight."

The actor locked himself in his apartment for a month prior to filming and estimated sleeping two hours per night for a week during filming because he couldn't stop thinking about the role. Crew members also worried about the actor, claiming he refused to speak to others out of character.

"If you tried to communicate with him normally instead of The Joker, he would just ignore you," a source told Fox News. "He would often come to the set to hang out even on his days off, freaking everyone out. Towards the end of filming, he was warned by people that he had gone too far."

"There was a sort of a sense of a figure eight to her walk, that her shoulders were back, it looked like she had a sort of - like a balloon was attached to her breastbone," Williams told CBS. "Her nipples were always pointed up... That was the work that I wanted to start as early as possible, because I don't want any of those thoughts to be anywhere in my mind when I'm in the middle of a scene."

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Kate Winslet spoke with a German accent at home.

Kate Winslet in "The Reader."
Weinstein Co.

While filming "The Reader," Winslet adopted a German accent and confused her kids when she kept it up at home.

"They got mightily fed up with me reading bedtime stories with a German accent," Winslet told The Sun. "They said, 'Mum, just be plain. Don't do any funny stuff like voices. Just be regular.'"

Joaquin Phoenix only responded to Johnny Cash's name on set.

Joaquin Phoenix undercover on "The Late Show With David Letterman" in February 2009.
CBS

During "Walk the Line," Phoenix took months to learn how to sing and play the guitar. He took it one step further when he asked the entire set to call him JR, Johnny Cash's real name.

"I'm embarrassed about it now," Phoenix told EW. "But when I heard 'Joaquin,' it just didn't feel right."

Phoenix shared he gets attached to all of his roles.

"When I did 'Gladiator,' I thought that I would carry a sword with me everywhere. When I did 'Ladder 49,' I didn't want to let go of my turnout gear, and I didn't believe that I could go through life without smelling smoke."

Phoenix later convinced most of the world that he had gone a bit crazy and given up acting to become a hip-hop artist after "Walk the Line." It turned out the entire bit was for a documentary "I'm Still Here," including his odd and awkward interview on Letterman.

Christian Bale lost an extreme amount of weight before gaining it back.

Christian Bale has gained and lost weight for many roles.
Francois Duhamel / Sony Pictures

Bale is the master of extreme weight loss and gain on screen.

To make himself look gaunt and sickly, Bale willingly dropped to 122 pounds for his role as insomniac, Trevor Resnick in "The Machinist" only eating a can of tuna and an apple a day.

"I was intrigued by a perverse nature of mine just to see if I can go beyond what I've been told is actually safe and OK, and see if I could push the limits," Bale told the BBC.

Bale quickly gained nearly 100 pounds of muscle afterward for his role as The Dark Knight in "Batman Begins." However, director Christopher Nolan saw that as too bulky for the Caped Crusader and ordered the actor to lose 20.

"I ate lots of doughnuts, a whole lot of cheeseburgers and whatever I could get my hands on. I literally ate anything that came my way," Bale told People magazine. "I was about 185 and went up to 228."

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Rooney Mara pierced her privates.

Rooney Mara in "The Girl with the Dragon Tattoo."
Columbia Pictures

Mara cut her hair, died it black, bleached her eyebrows, and pierced her nipples to play infamous computer hacker, Lisbeth Salander, in "The Girl with the Dragon Tattoo."

"Before, I dressed much girlier," said Mara. "A lot of blush-colored things. Now I literally roll out of bed and put on whatever is there. I have really enjoyed being a boy this last year."

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Shia LaBeouf actually dropped acid.

Shia LaBeouf.
Matt Winkelmeyer/Getty Images

The "Transformers" actor has pushed himself to make his latest roles seem as realistic as possible.

He said he took acid to understand the effects of the drug on his character in "The Necessary Death of Charlie Countryman." He also had sex on screen for Lars Von Trier's film "The Nymphomaniac."

LaBeouf told USA Today in 2012 that he sees his experiments as fine as long he doesn't go too far.

"I have ethics, I'm not completely out of my mind," said LaBeouf. "But I don't think there's anything wrong with sex. Sex is beautiful if it's done right. And I wouldn't just do it for no reason … Sex is different than love, and there is a separation, and that middle gap is what the movie's about."

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Jim Carrey never stopped being Andy Kaufman while making "Man on the Moon."

"There's probably no one who understands Method acting better academically than I do, or actually uses it more in his work," Nicholson told Esquire as he recounted a call he had with Sean Penn. "But it's funny —nobody really sees that. It's perception versus reality, I suppose."

In 1986, The New York Times published a lengthy piece on " the method and mystique" of Nicholson. The actor sang drawn-out rendition of "Three Blind Mice" for the newspaper to show them a method acting exercise he was taught by one of his acting teachers.

Tilda Swinton asked for a very special set of prosthetics to play an 82-year-old man in "Suspiria."

According to The New York Times, Swinton's makeup took up to four hours each day.Amazon Studios

The actress does double-time playing two characters in the movie. Swinton asked Oscar-winning makeup artist Mark Coulier to create male genitalia for her to wear on set of the movie as she played the psychoanalyst, Josef Klemperer.

"She did have us make a penis and balls," Coulier told the NYT. "She had this nice, weighty set of genitalia so that she could feel it dangling between her legs, and she managed to get it out on set on a couple of occasions."